Leadless pulse generators have a helical anchor at a distal end of the leadless pulse generator. The helical anchor is used to secure the leadless pulse generator to cardiac tissue in such a manner that an electrode of the leadless pulse generator is maintained in appropriate tissue contact for cardiac pacing and sensing.
Since the helical anchor is fixed relative to the rest of the leadless pulse generator, the leadless pulse generator is rotated as a whole relative to the cardiac tissue to cause the helical anchor to screw into the cardiac tissue and thereby fix the leadless pulse generator to the cardiac tissue. Implanters make use of a chevron or other shaped radiopaque marker within the body of the device for visual feedback under fluoroscopy when rotating the leadless pulse generator to screw the helical anchor into the cardiac tissue.
A prescribed number of turns (e.g. 1¼ turns) of the leadless pulse generator is recommended for desirable helical anchor fixation in the cardiac tissue. However, verifying that the prescribed number of turns has actually resulted in actual turns of the helical anchor screwing into the cardiac tissue can be a challenge. This challenge results from the fact that the leadless pulse generator may be rotated for the prescribed number of turns without the helical anchor fully engaging the cardiac tissue for the entirety of the prescribed number of turns, and the radiopaque marker viewed via fluoroscopy only conveys to the implanter that rotation of the leadless pulse generator is occurring, not that the helical anchor is properly screwing into cardiac tissue.
Consequently, there is a need in the art for an improved leadless pulse generator configuration and related methods of manufacture and use.